The field of this invention is that of carrier artillery shells.
Carrier shells are projectiles intended to transport a payload and then release it at a point in the projectiles' trajectory.
The payload can be, for example, an illuminating charge or can consist of a stack of several submunitions.
French patent FR 2 363 077 describes one such type of shell which comprises a casing closed at one of its ends by a base and at the other by a head. A gas-generating pyrotechnic composition is placed inside the head, wherein the composition is ignited by a timer fuse to create gas pressure which acts on a piston. The thrust exerted by the piston on the stack of submunitions causes separation of the base and casing of the projectile, then ejection of the submunitions from the casing.
Such carrier shells are most often gyroscopically stabilized by being g fired from a gun with a rifled barrel. This then raises the problem of how the payload is to be spun by the carrier shell.
U.S. Pat. No. 4,771,696 proposes a carrier shell in which a band placed on the casing causes the latter to be spun by the rifling of the barrel of the weapon. The casing has, on its inside cylindrical surface, radial notches which interact with complementary lugs present on the outside surface of a base. The base contacts the payload by means of a collar having notches arranged in an axial direction which interact with corresponding lugs on the payload. The base is kept in contact with the payload by means of a threaded ring.
This kind of solution is relatively complex, since it requires the creation on the base of notches in radial and axial directions.
In addition, the casing of the carrier shell disclosed in the 696 patent is generally relatively thin in order to allow carriage of a large payload, which limits the depth of the radial notches and therefor their mechanical strength.
Lastly, with the type of configuration disclosed in the 696 patent, gas leaks are possible between the base and the threaded retention ring, making it essential to provide a rear extension which is threaded onto the base and which presses against the rear of the casing.
The rear extension constitutes an additional part which must be manufactured, procured, and installed on the shell, which is detrimental in terms of cost. Moreover, it requires additional machining to allow installation on the base.
The purpose of the present invention is to provide a carrier shell in which the means allowing the payload to be spun are of a simple and low-cost design, while possessing excellent mechanical strength.
The shell proposed by the invention can also be easily adapted to a payload with a different mass, with no alteration in the mechanical strength of the carrier shell.